#include <iostream>
#include <string>
using namespace std;
int main()
{
	string s;
	cin >> s;
	int begin = -1, len = 0;
	for (int i = 0; i < s.size(); i++)
	{
		if (s[i] >= '0' && s[i] <= '9')
	{
			int j = i;
			while (j < s.size() && s[j] >= '0' && s[j] <= '9') j++;
			if (j - i > len)
			{
				begin = i;
				len = j - i;
			}
			i = j;
		}
	}
	if (begin == -1) cout << "" << endl;
	else cout << s.substr(begin, len) << endl;
	return 0;
}